Simultaneous plasticization and blending of isolated soy protein with poly(butylene succinate-co-adipate)

International audienceAgrarian proteins, due to their good film forming properties, moderate cost, and biodegradable nature, have been extensively studied to develop affordable packaging materials. However, when compared to conventional polymers, isolated proteins based polymers have poor mechanical and barrier properties. Blending with others polymers seems to be a viable option to overcome these issues. The present work focuses on the preparation of isolated soy protein (ISP) / poly[(butylene succinate)-coadipate] (PBSA) blends with different ratios by extrusion and injection moulding using glycerol and water mixture as plasticizer. PBSA is bio-based, biodegradable, and its relatively low melting point is compatible with the processing temperature of ISP. Two different processing strategies were used and compared for the preparation of blends. In the novel single step approach, ISP, plasticizers (glycerol and water) and PBSA are dry mixed and extruded all together in a co-rotating twin-screw extruder. In the regular two-step approach, plasticized protein is prepared by extrusion of ISP with a glycerol/water mixture, followed by a second extrusion step of plasticized protein with PBSA. Prepared blends were characterized for their morphology, thermal, dynamic mechanical and mechanical properties. The mechanical properties of the blends prepared by single step process are roughly similar to those produced by two-step process; this indicates the efficiency of one-step melt processing of PBSA with isolated soy protein involving plasticization, denaturation, melt-melt mixing and morphology development in the extruder, this compounding method being moreover less time consuming

LA SEÑORA [Material gráfico]

Copia digital. Madrid : Ministerio de Educación, Cultura y Deporte. Subdirección General de Coordinación Bibliotecaria, 201

Long-chain branched poly(butylene succinate-co-terephthalate) copolyesters: Impact of (reactive) synthesis strategies on melt strength properties

peer reviewedHighly biobased poly(butylene succinate-co-terephthalate) (PBST) with processing temperatures close to those of commodity polymers (160–180°C) and long-chain branched architectures (LCB) are synthesized by different strategies. Their rheological properties are investigated, in particular their melt strength properties. A two-step synthesis route is first proposed based on linear LCBs produced by polycondensation followed by reactive extrusion with an epoxy-based multifunctional agent Joncryl® at concentrations up to 2 wt%. A one-step synthesis strategy is also developed using glycerol as a branching agent, introduced at a low concentration (0.5 wt%) directly during the PBST polycondensation process. The molecular weights, LCB structures, and thermal properties are determined by triple detection size exclusion chromatography and differential scanning calorimetry. For PBSTs synthesized in two steps, gelation takes place simultaneously with the branching reactions. However, a concentration of Joncryl® close to 2 wt% is required to improve the melt strength properties, with strain hardening effects under elongation conditions. Interestingly, PBSTs synthesized by in-situ addition of glycerol show remarkable melt strength and a high melt stabilization process. Dynamic rheology investigations allow attributing these effects to statistical/ho-mogeneous gel-free LCB architectures obtained during reactive extrusion without any additional post-processing. The effec-tiveness of approaches to easily improve the melt strength of highly biobased aliphatic-aromatic copolyesters (theoretical biobased content up to 85%) and to eliminate extrusion defects/instabilities in PBSTs is thus demonstrated, allowing the pos-sibility of expanding the industrial application domains of these polymers in packaging and sustainable applications

REMEDIOS MESA DE LEÓN [Material gráfico]

ÁLBUM FAMILIAR CASA DE COLÓNCopia digital. Madrid : Ministerio de Educación, Cultura y Deporte. Subdirección General de Coordinación Bibliotecaria, 201

MARUCA PENICHET, MISS GRAN CANARIA. [Material gráfico]

** DE PLACA ORIGINAL ADQUIRIDA POR EL COLECCIONISTA EN LAS PALMAS DE GRAN CANARIAFOTO DE RETRATO DE SEÑORITA CON MANTILLA VISTA DESDE CINTURA. MISS GRAN CANARIA. MARUCA PENICHETCopia digital. Madrid : Ministerio de Educación, Cultura y Deporte. Subdirección General de Coordinación Bibliotecaria, 201

Study of partial shape memory effect of polymers by multicycle tests

In this work, an experimental investigation on a partial shape memory polymer (PSMP) which is transformed into shape memory material is presented. Multicycle shape memory tests are performed on thermoplastic polyurethane (TPU) at 70°C. At the end of each cycle, the capacity of the shape memory material increases. At the end of the first cycle, the recovery rate of TPU is only 67%; this partial shape memory effect (PSME) has been improved by successive cycles of shape memory tests. After the fourth cycle, it becomes nearly 100% shape memory material. The results of the fifth and sixth cycles confirm this modification. These original results indicate that a polymer with partial shape memory may be transformed into an SMP without any chemical modification. This increase of SME could be related to the creation of residual stresses during the tensile tests. The residual stresses are the origin of the driving force responsible for SME

Assessment of the elongational properties of HIPS membranes based on full-field strain measurements during positive thermoforming

International audienceIn the field of experimental mechanics, interest is more and more attributed to designing original single multiaxial tests which can exhibit heterogeneous mechanical responses for parameters identification. In fact, classical identification procedures of biaxial thermoplastic properties which rely on simple isotropic behavior obtained from uniaxial mechanical tests generally lack precision. Such aspect is mostly confirmed by the inaccuracy of the mechanical behavior when the same parameters identified from uniaxial loads are used in multiaxial cases. Membrane inflation constitutes one particular example of biaxial loading tests. It is characterized by imposing combined but different stretching levels along the principle directions [1,2]. The pole region is submitted to equibiaxial stretching whereas the regions near the base of the spherical shape are submitted to planar tension. As reported in literature, with the use of optical measurement techniques such as stereo digital image correlation (S-DIC) analysis of strain full-fields, the identification of material parameters of elastomers [3] or biological tissues [4] has become more reliable. Moreover, biaxial load configurations have various forms and can even be performed during the shaping of plate sheets via the thermoforming process. As recently reported by Van Mieghem et al., S-DIC has the potential to monitor large out-of-plane deformations taking place during thermoforming. The authors provided an original experimental procedure for validation of plastic-processing simulation packages based on thickness distribution under the assumption of material incompressibility [5,6]. In the present study, by investigating a different case from the previously stated authors, we shed more light on the potential of stereo digital image correlation (S-DIC) and positive thermoforming for identification of elongational properties of a high impact polystyrene (HIPS) at different temperatures (higher than its glass transition). In this context, an industrial thermoforming machine (Illig Ed100) is used. A thin thermoplastic sheet is pre-heated and pre-stretched at the rubbery state by applying an air-flow to form a spherical bubble of almost 55 mm radius within 1.5 seconds duration. Then, the pre-stretched sheet is further deformed by using a large wooden positive mould (Figure 1). This mould has a particular form which imposes a large out-of-plane displacement level of 250 mm at less than 2 seconds. During the mechanical deformation the sheet surface temperature is monitored using multiple thermocouples. Complementarily, a pressure sensor (of the type JUMO AP-30) is used to measure the air pressure during the inflation phase. Material deformations during the whole thermoforming cycle are monitored by using a S-DIC system from LaVision equipped with two 4M pixels cameras that allow detection of a set of pair images at 150 fps at a full resolution of (2048×2048 pixels). Only the full-field strain data evaluated during the plate membrane inflation step will be presented (up to 55 mm /250 mm), in the current study. First, the displacement profiles during the mechanical load along the principle directions will be used to confirm the axisymmetry of the problem. Second, the full-field experimental data at the polar region will be used for identification of the material elongational parameters of a hyperelastic model such as the Mooney-Rivlin model (classically used for HIPS) by using a Finite Element Model Updated (FEMU) procedure [7,8]. Boundary conditions and preliminary results of the identification procedure will be presented. Finally, with respect of the assumption of material incompressibility, the validation procedure will be based on the comparison between numerically calculated and experimental measured thickness distributions along the major axes of the HIPS sheet

Engineer training and e-learning at Douai

International audienc

Le recyclage des composites

National audienc

Engineer training and e-learning at Douai

International audienc